Liquid phase selective hydrogenation of cinnamaldehyde over copper supported catalysts

The selective hydrogenation of cinnamaldehyde is carried out in a batch reactor, at 100 degrees C and 1 MPa of H-2 using isopropyl alcohol as the solvent, over a series of copper supported catalysts: Cu/Al2O3, Cu/SiO2 Cu/MCM-48, Cu/CeO2 and Cu/alpha-Fe2O3. The selectivity of the samples is compared with that corresponding to Pti/SiO2. Reduced Cu/Al2O3 and Cu/SiO2 showed lower selectivity to the cinnamyl alcohol (16-22%) than Pt/SiO2 (35%), at 15% of conversion. Following a calcination at 300 degrees C both, activity and selectivity of copper catalysts were increased. The calcined surface would hydrogenate C=O bond by hydrogen transfer from the solvent. TPR, XRD and FUR of adsorbed CO showed that Cu (I) species are stabilized on the mesoporous structure of MCM-48. This particular feature renders Cu/MCM-48 a selective catalyst, reaching high selectivity values (51%, at 15% of conversion). Cu/CeO2 and Cu/alpha-Fe2O3 showed higher selectivity than Pt based catalyst due to a promotion of the catalytic properties of copper by reduced support species. (C) 2011 Elsevier B.V. All rights reserved.